Method of disassembling articles



. May 11, 1948. I E. GOSMANN EI'AL 2,441,353

us'rnon OF DI-SASSEMBLING ARTICLES Filed Sept. 26, 1946 2 SheetsSheet 1 IN V5 7' 0/93 E. GOSMA/V/V KA. WESTON a) May 11, 1948. E. GOSMAN N ETAL 2,441,353

METHOD OF DISASSEMBLING ARTICLES Filed Sept. 26, 1946 2 Sheets-Sheet 2 Patented May 11 i948 METHOD or msasssnmuuo narrows Enart Gosmann, Elmwood Park, Ill., and Keith A. Weston. St. Paul, Minn., assignors to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York I Application September 26, 1946, Serial No. 699,412

1 9' Claims. This invention relates to methods of disassembling articles, and more particularly to a method of removing brazed parts from defective vacuum tube assemblages for subsequent repair of the tubes.

An object of this invention is the provision of an eflicient and effective method of removing brazed parts from assemblages without deleterious effect thereto.

In accordance with the above object of this invention as practiced in connection with the disassembling of vacuum tubes for subsequent repair, in which the tubes are provided with copper end caps solder-brazed to a copper body for closing opposite ends of a central cavity therein and to which are sealed one or more glass envelopes communicating with the central cavity, an acetylene torch is applied to the brazed joints, one at a time, while the tube is supported in a fixture having two pressure pads, one for each cap, with thepad for the cap being removed retracted therefrom and the pad for the following cap to be removed pressing thereon. Simultaneously therewith, a mixture of carbon dioxide and methanol vapor gas or other suitable protective and reducing atmospheres is applied under pressure through one of the envelopes to the central cavity of the tube body to purge it of air and thus prevent oxidation thereof. When the solder is suificiently softened, the gas pressure is suddenly increased inside the tube to blow the cap oif the body, thus insuring that the inside surfaces of the tube are maintained clean and free of oxides. While the applied increased gas pressure is still flushing out through the opening left by the removed cap, the associated spaced pressure pad is permitted to move over the opening to seal the same, whereupon the pad associated with the second cap is withdrawn therefrom and thereafter, in a manner similar to that described above, the second cap is released and blown off the tube body.

Other objects and advantages of this invention will more fully appear from the following detail description taken in conjunction with the accompanying drawings which illustrate an apparatus by means of which the method may be practiced, in which Fig 1 is an elevational view of an apparatus used in practicing the method showing a vacuum tube mounted thereon in preparation of removing the brazed end caps thereupon in succession;

Fig. 2 is a fragmentary plan view thereof and Fig. 3 is a vertical sectional view taken on the line 3-3 of Fig. 2.

Referring to the drawings in detail, and particularly to Figs. 1 and 3, wherein the invention has been applied to the disassembling of one type of vacuum tube assemblage, indicated in general by the numeral I0. Such an assemblage comprises and includes, among other elements, a rectangular shaped copper shell or body II having a pair of cooling fins I2 projecting from two angularly arranged faces of the body. Formed in the ends of the fins I2 is a pair of aligned apertures I3, which are used for attaching to the tube an element (not shown), which cooperates with the tube when in use. Opposite ends of a central cavity I4 in the body I I are provided with copper end covers or caps I l which are sealed to the body .by ring-shaped pieces of silver solder I8 fused during a brazing operation to unite the caps to the body. Sealed to the body I I are closed glass envelopes I8 and 20, which communicate with the central cavity I4 by means of apertures 23 and 24, respectively (Fig. 3) formed in the body. In order to salvage a tube assemblage II) which has become defective, for one reason or another, it is necessary, for the purpose of gaining access to the centralcavity ll of the body II, to repair its defectiveness to remove the caps I1 therefrom withoutdeleterious eifect to the assemblage I0. For this purpose, the following described method and an apparatus for facilitating the practice of the method has been devised.

One form of the apparatus may comprise a base plate 25 provided with two spaced standards 28 upon which is pivoted as indicated at 3030, a table-like member 3I adapted to be rotated to present either of its main faces uppermost and horizontal and when so positioned to be maintained thereat by locking pins 32 enterable into aligned apertures in the standards 26 and pivots 30-30 when the member 3| has been rotated from one position to the other. Formed in the member 3| is a rectangular shaped opening 33 and attached to one main face of the member and extending along two sides of the opening is an L-shaped member 34 which is under-cut, as

indicated at 31 (Fig. 3), along its bottom face with the member 3| in the position shown in the several figures of the drawing. Formed integral with the member 3i and extending from its main faces are L-shaped arms 38 and 39 having aligned sleeve-like portions Ill upon their freev ends, which portions are disposed perpendicular to the main faces oi the member 3 I. Reciprocable in the portions III or the arms 3| and 39 are rods 4| having handle portions 48 at their outer ends and carrying circular pads 44 at their inner ends. Coiled compression springs 45 surrounding the rods 4| and abutting opposed faces of the sleeve-like portions 40 and the pads 44 serve to move the pads toward each other into their operative positions unless they are held in their retracted positions by laterally extending pins 48 carried by the rods 4| and arranged to rest upon the outer end faces of the sleeve-like portions 40, as shown in Fig. 1, in the position of the upper pad 44. When the pads 44 are to be moved to their operative positions, as sh own in Figs. 1 and 3, to the position of the lower pad, the rod 4| is rotated 180 to align the pin 46 resting at the time upon the outer end face of the sleeve-like portion 40 with a slot 41 formed longitudinally in the inner periphery of the portion 40 and the rod is then lowered to enter the pin in the slot, the

slot being of such length that the pad 44 will reach its operative position under the pressure of the spring 45 before the pin engages the bottom of the slot.

In practicing the method of disassembling or removing the caps i1 from the described type of vacuum tube assemblage l with the hereinbeiore described apparatus, the assemblage is first mounted in the apparatus, as shown in the drawings, by sliding the assemblage into position upon the L-shaped member 34 to the position shown in Figs. 2 and 3, whereupon a locking pin 48 is inserted through the aligned apertures iii in the pins l2, disposed at opposite faces of the member 34 and an aperture in the member 34. At the time the assemblage I0 is thus mounted on the apparatus, the pads 45, coaxially aligned with the caps l1, are retained in their retracted positions in the manner previously described, as shown by the position of the upper pad 44 in Fig. 2 and the table-like member 3| is locked in a horizontal position by the pins 32 previously described. 'The lower pad 44 is then released and permitted to press against the lower cap I! while the upper pad 44 remains retracted, as shown in Fig. 1.

While thus mounted on the apparatus, a mixture of carbon dioxide gas (CO2) and methanol vapor or other suitable protective atmosphere and reducing agent is directed to the interior cavities of the tube assemblage I0 by means of a rubber hose 49 inserted over a tubular extension or tip 50 on the glass envelope l9, the extension 50 being first opened to permit communication with the interior of the assemblage. The flow of the above-described gas may be controlled by a suitable valve 5|, illustrated diagrammatically in Fig. 2, which is connected by conduits 52 and 53 to low and high pressure sources of gas, respectively (not shown). The interior of the tube assemblage is first flushed of air with low pressure gas supplied through the conduit 52, valve 5| and hose 49, using a by-pass or.

outlet nozzle 56 in the conduit 52 to reduce the pressure of the gas to approximately atmospheric pressure. During the flushing of the interior of the tube assemblage, a suitable flame from a hand-directed acetylene torch 51 is played on the brazed joint of the cap i1 to the body II and, upon the operator observing that the solder i has melted, the excess solder is wiped off with a brush and then the valve 5| is quickly operated to connect the high pressure gas through the conduit 53,.valve 5| and hose 49 to the interior of the tube assemblage'which serves to blow the released cap I1 01! the body without deleterious 4 eflect on the assemblage. In addition, the inside suriaces of the assemblage will be maintained clean and free of oxides.

During the application or the high pressure gas. it will be understood that the low pressure gas connected to the conduit "is cut oil! so that the valve 5| is not connected to atmosphere by means of the nozzle I4. Before applying the flame from the acetylene torch, it is desirable to preheat the assemblage In to prevent damage thereto from the sudden application or the intense heat from the torch flame. This may be accomplished by playing flames of low intensity on the assemblage from a burner during the flushing operation or by placing the assemblages on a hot plate previous to their mounting on the appar-atus.

Following this last described step, and while the high pressure gas is still flushing out through the opening left by the removed cap ill, the spring-pressed pad 44, which is retracted Irosn the opening, is released and lowered to engage the body I! and thus sealing the opening. Thereafter, the locking pins 92 are withdrawn and the table-like member 3| is rotated about its pivots 39-30 and the pins reinserted to lock the member 3| in its newly rotated position. During the rotation of the table-like member 3|, the rubber hose 49 is left connected to the glass envelope I9, the hose being of suflicient length to permit this rotation of the member 3! without disturbing its connections to the valve 6| or the glass envelope Ii. With the member 3| in the latter position, the pad 44 previously in the lowermost position, as shown in Fig. 2, is now in the uppermost position, whereupon it is retracted from the associated cap I1 and retained in its retracted position in the manner previously described. The valve 5| is now operated to connect the low pressure gas to the interior of the assemblage and, in the manner similar to that described hereinbefore, the second cap I1 is released and blown oil the tube body II.

What is claimed is:

l. The method of removing from a normally sealed hollow article an element brazed thereto for closing an opening to the interior of the article which comprises providing another opening to said interior, applying a protective gas through said other opening to flush said interior, subjecting the joint of brazing to sufllcient heat to melt the brazing material, and while the brazing material is molten, increasing the pressure of said protective gas to said interior sufficiently to blow the element from the article.

2. The method of removing from a normally sealed hollow article an element solder brazed thereto for closing an opening to the interior of the article which comprises providing another opening to said interior, applying carbon dioxide gas under approximately atmospheric pressure through said other opening to flush said interior, subjecting the joint of brazing to sufficient heat to melt the solder, and while the solder is molten, suddenly increasing the pressure of said carbon dioxide gas to said interior sufilciently to blow the element from the article.

3. The method of removing from a normally sealed hollow article an element brazed thereto for closing an opening to the interior of the article, which comprises providing another opening to said interior, applying a carbon dioxide and methanol vapor gas through said other opening to flush said interior, subjecting the Joint of brazing to suflicient heat to melt the brazin article to fuse the brazing material and, upon the brazing material becoming fused, suddenly increasing the pressure of the reducing gas to flow the element lfrom. the article.

5. The method of removing from a normally sealed hollow article an element brazed thereto for closing an opening to the interior of the article which comprises providing another opening to the interior of the article, flushing the interior of the article with a reducing gas through said other opening, simultaneously heating the article to fuse the brazing material and, upon the brazing material becoming fused, suddenly increasing the pressure of the reducing gas to flow the element from the article and continuing the flushing of the reducing gas through the article until the article is sufliciently cooled to reduce the possibility of an excess of oxide forming on the article.

6. The method of :removing from a normally sealed hollow article an element brazed thereto for closing an opening to the interior of the article which comprises providing another opening to the interior of the article, directing a reducing gas at low pressure to the interior oi. the article through said other opening to flush oxidizing gases from the interior of the article, heating the article during the flushing thereoi.

to fuse the brazing material, holding the element on the article during said flushing opera-v tion, suddently increasing the pressure of the reducing gas when the brazing material becomes fused to forciby eject the element from the article, and continuing to flush the interior of the article with said reducing gas to prevent oxidation of the interior thereof.

'1. The method of removing from a normally sealed hollow article elements brazed thereto for closing openings to the interior of the article which comprises providing another opening to the interior of the article, flushing the interior of the article with a reducing gas through said other opening, simultaneously heating the article to fuse the brazing material at said one element, suddenly increasing the pressure of the reducing gas to blow said one element from the article, and sealing the openingto the article formed by blowing said one element from the article during the removal of a second element from the article.

8. The method of removing from a normally sealed hollow article elements brazed theerto for closing openings to the interior of the article which comprises providing another opening to the interior of the article, directing a reducing gas at low pressure to the interior of the article through said other opening to flush oxidizing gases from the interior of the article, simultaneously heating the article to fuse the brazing material, and, upon the brazing material at said one element becoming dzused, suddenly.increasing the pressure of the reducing gas to forcibly eie'ct'said one element from the article, continuing to flush the interior of the article with said reducing gas of increased pressure to prevent oxidation of the interior thereof, and resiliently sealing the opening to the article formed by blowing said one element from the article while the flushing continues and during the removal of a second element from the article.

9. 'I'hemethod of removing from a normally sealed vacuum tube a cover brazed to the body of the tube for closing an opening to the interior of the tube in communication with a glass envelope having a closed tubular extension which comprises providing an opening in the tubular extension, flushing the interior of the tube with a reducing gas through said opening in the tubular extension, simultaneously heating the body of the tube to fuse the brazing material and, upon the brazing material becoming fused,

suddenly increasing the pressure or the reducing gas to blow the cover from the body of the tube.

ENART GOSMANN. KEITH A. WESTON.

REFERENCES CITED The following references are or record in the 6 file of this patent:

STATES PATENTS Number Name Date 2,342,045 Fuller Feb. 15, 1944 

